This invention relates generally to the manufacture of ceramic capacitors, and more particularly concerns the adjustment of dielectric constants of capacitors to desired levels.
The dielectric constants of ceramic materials, such as BaTiO.sub.3 for example, is greatly increased by the technique of so called hot-press sintering. See for example "Gas Isostatic Hot Pressing Without Molds" by K. H. Hardtl published in Vol. 54, No. 2 (1975) of Ceramic Bulletin, Am. Ceramic Society; see also "Properties of Hot-Pressed Barium Titanate" by Arthur Brown and Robert Fischer, published in USASRDL Technical Report 2196 for April 1961. The hot pressing effect is facilitated by high isostatic gas pressure on the order of 50 to 100 atmospheres at elevated sintering temperature. Thus, hot-pressed BaTiO.sub.3 typically exhibits a dielectric constant in excess of 3000 as compared with conventionally sintered BaTiO.sub.3 exhibiting a dielectric constant of about 1000.
There remains a need, however, to provide accurate and controlled, high dielectric constants in such hot-pressed ceramic materials, as for example at dielectric constant levels less than 3000.